Home Office claims national security exemption to my FOI request about all things related to Silk Road and Bitcoin:

Information which does not fall within subsection 23(1) is exempt information if exemption from section 1(1)(b) is required for the purpose of safeguarding national security. (2) The duty to confirm or deny does not arise if, or to the extent that, exemption from section 1(1)(a) is required for the purpose of safeguarding national security.